- LATEX EXTRACTABLES OF CALOTROPIS GIGANTEA
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The hexane and methanol soluble extract of the latex coagulum of Calotropis gigantea afforded two new triterpene esters, viz. 3'-methylbutanoates of α-amyrin and ψ-taraxasterol, besides the known 3'-methylbutanoates of three triterpene alcohols.The compositions of the alkane fraction, total triterpene alcohol fraction, and free, acetyl and 3'-methylbutanoyl triterpene alcohol fractions of the extract were determined.Key Word Index- Calotropis gigantea; Asclepiadaceae; latex; 3'-methylbutanoyl, acetyl and free α-amyrin, β-amyrin, ψ-taraxasterol, taraxasterol and lupeol; alkanes.
- Thakur, Swapnadip,Das, Prantika,Itoh, Toshihiro,Imai, Kazunori,Matsumoto, Taro
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- Antiprotozoal glutathione derivatives with flagellar membrane binding activity against T. brucei rhodesiense
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A new series of N-substituted S-(2,4-dinitrophenyl)glutathione dibutyl diesters were synthesized to improve in vitro anti-protozoal activity against the pathogenic parasites Trypanosoma brucei rhodesiense, Trypanosoma cruzi and Leishmania donovani. The results obtained indicate that N-substituents enhance the inhibitory properties of glutathione diesters whilst showing reduced toxicity against KB cells as in the cases of compounds 5, 9, 10, 16, 18 and 19. We suggest that the interaction of N-substituted S-(2,4-dinitrophenyl) glutathione dibutyl diesters with T. b. brucei occurs mainly by weak hydrophobic interactions such as London and van der Waals forces. A QSAR study indicated that the inhibitory activity of the peptide is associated negatively with the average number of C atoms, NCand positively to SZX,the ZX shadow a geometric descriptor related to molecular size and orientation of the compound. HPLC-UV studies in conjunction with optical microscopy indicate that the observed selectivity of inhibition of these compounds against bloodstream form T. b. brucei parasites in comparison to L. donovani under the same conditions is due to intracellular uptake via endocytosis in the flagellar pocket.
- Daunes, Sylvie,Yardley, Vanessa,Croft, Simon L.,D'Silva, Claudius
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- Synthesis, pH dependent, plasma and enzymatic stability of bergenin prodrugs for potential use against rheumatoid arthritis
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Bergenin is a unique C-glycoside natural product possessing anti-inflammatory and anti-arthritic activity. It is hydrophilic molecule and stable under acidic conditions however is unstable at neutral-basic pH conditions. The rate of degradation is directly proportional to the increase in pH which might be one of the reasons for its low oral bioavailability. Thus, herein our objective was to improve its stability using prodrug strategy. Various ester and ether prodrugs were synthesized and studied for lipophilicity, chemical stability and enzymatic hydrolysis in plasma/esterase. The stability of synthesized prodrugs was evaluated in buffers at different pH, in biorelevant media such as SGF, SIF, rat plasma and in esterase enzyme. All prodrugs displayed significantly improved lipophilicity compared with bergenin, which was in accordance with the criteria of drug-like compounds. Acetyl ester 4a2 appeared to be the most promising prodrug as it remained stable at gastric/intestinal pH and was completely transformed to the parent compound bergenin in plasma as desired for an ideal prodrug. The data presented herein, will help in designing stable prodrugs of unstable molecules with desired physicochemical properties in structurally similar chemotypes.
- Singh, Rohit,Kumar, Vikas,Bharate, Sonali S.,Vishwakarma, Ram A.
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Read Online
- Synthesis of (-)-Indolactam V
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A stereospecific 7-step synthesis of (-)-indolactam V 1 from tryptophan methyl ester is described.The key steps are the photocyclisation of the dichloroamide 6 to give the isomeric 7-hydroxy-7-isopropylpyrrolobenzazocines 16 + 18 and the nitrene-mediated ring expansion of the derived azide 5 to give the 9-membered imine 4.The synthesis is completed by stereoselective reduction of the imine bond and N-methylation.
- Mascal, Mark,Moody, Christopher J.,Slawin, Alexandra M. Z.,Williams, David J.
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Read Online
- Preparative synthesis of vanillin and vanillal alkanoates
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Procedures for preparing vanillin and vanillal alkanoates were developed.
- Dikusar,Vyglazov,Moiseichuk,Zhukovskaya,Kozlov
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Read Online
- A Diverse Library of Chiral Cyclopropane Scaffolds via Chemoenzymatic Assembly and Diversification of Cyclopropyl Ketones
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Chiral cyclopropane rings are key pharmacophores in pharmaceuticals and bioactive natural products, making libraries of these building blocks a valuable resource for drug discovery and development campaigns. Here, we report the development of a chemoenzymatic strategy for the stereoselective assembly and structural diversification of cyclopropyl ketones, a highly versatile yet underexploited class of functionalized cyclopropanes. An engineered variant of sperm whale myoglobin is shown to enable the highly diastereo- and enantioselective construction of these molecules via olefin cyclopropanation in the presence of a diazoketone carbene donor reagent. This biocatalyst offers a remarkably broad substrate scope, catalyzing this reaction with high stereoselectivity across a variety of vinylarene substrates as well as a range of different α-aryl and α-alkyl diazoketone derivatives. Chemical transformation of these enzymatic products enables further diversification of these molecules to yield a collection of structurally diverse cyclopropane-containing scaffolds in enantiopure form, including core motifs found in drugs and natural products as well as novel structures. This work illustrates the power of combining abiological biocatalysis with chemoenzymatic synthesis for generating collections of optically active scaffolds of high value for medicinal chemistry and drug discovery.
- Nam, Donggeon,Steck, Viktoria,Potenzino, Robert J.,Fasan, Rudi
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p. 2221 - 2231
(2021/02/16)
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- Design and Synthesis of Natural Product Inspired Libraries Based on the Three-Dimensional (3D) Cedrane Scaffold: Toward the Exploration of 3D Biological Space
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A chemoinformatic method was developed to extract nonflat scaffolds embedded in natural products within the Dictionary of Natural Products (DNP). The cedrane scaffold was then chosen as an example of a nonflat scaffold that directs substituents in three-dimensional (3D) space. A cedrane scaffold that has three orthogonal handles to allow generation of 1D, 2D, and 3D libraries was synthesized on a large scale. These libraries would cover more than 50% of the natural diversity of natural products with an embedded cedrane scaffold. Synthesis of three focused natural product-like libraries based on the 3D cedrane scaffold was achieved. A phenotypic assay was used to test the biological profile of synthesized compounds against normal and Parkinson's patient-derived cells. The cytological profiles of the synthesized analogues based on the cedrane scaffold revealed that this 3D scaffold, prevalidated by nature, can interact with biological systems as it displayed various effects against normal and Parkinson's patient-derived cell lines.
- Tajabadi, Fatemeh Mazraati,Pouwer, Rebecca H.,Liu, Miaomiao,Dashti, Yousef,Campitelli, Marc R.,Murtaza, Mariyam,Mellick, George D.,Wood, Stephen A.,Jenkins, Ian D.,Quinn, Ronald J.
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p. 6609 - 6628
(2018/07/25)
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- Photoinduced, Copper-Catalyzed Decarboxylative C-N Coupling to Generate Protected Amines: An Alternative to the Curtius Rearrangement
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The Curtius rearrangement is a classic, powerful method for converting carboxylic acids into protected amines, but its widespread use is impeded by safety issues (the need to handle azides). We have developed an alternative to the Curtius rearrangement that employs a copper catalyst in combination with blue-LED irradiation to achieve the decarboxylative coupling of aliphatic carboxylic acid derivatives (specifically, readily available N-hydroxyphthalimide esters) to afford protected amines under mild conditions. This C-N bond-forming process is compatible with a wide array of functional groups, including an alcohol, aldehyde, epoxide, indole, nitroalkane, and sulfide. Control reactions and mechanistic studies are consistent with the hypothesis that copper species are engaged in both the photochemistry and the key bond-forming step, which occurs through out-of-cage coupling of an alkyl radical.
- Zhao, Wei,Wurz, Ryan P.,Peters, Jonas C.,Fu, Gregory C.
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supporting information
p. 12153 - 12156
(2017/09/12)
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- NOVEL COMPOSITIONS, USES AND METHODS FOR THEIR PREPARATION
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The present invention relates to novel compunds and pharmaceutical compositions thereof which may be useful in the treatment and/or prevention of various conditions. The present invention also provides methods of prearing such compounds and compositions, and methods of using the same.
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Paragraph 0271; 0272
(2015/05/05)
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- BENZOPIPERAZINE COMPOSITIONS AS BET BROMODOMAIN INHIBITORS
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The present invention relates to inhibitors of bromo and extra terminal (BET) bromodomains that are useful for the treatment of cancer, inflammatory diseases, diabetes, and obesity, having Formula (I): wherein X, Y, Z, R1, R2, R4 and R7 are defined herein.
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Paragraph 00407
(2015/06/03)
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- Synthesis of coenzyme A thioesters using methyl acyl phosphates in an aqueous medium
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Regioselective S-acylation of coenzyme A (CoA) is achieved under aqueous conditions using various aliphatic and aromatic carboxylic acids activated as their methyl acyl phosphate monoesters. Unlike many hydrophobic activating groups, the anionic methyl acyl phosphate mixed anhydride is more compatible with aqueous solvents, making it useful for conducting acylation reactions in an aqueous medium.
- Pal, Mohan,Bearne, Stephen L.
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supporting information
p. 9760 - 9763
(2015/01/08)
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- Design and synthesis of systemically active metabotropic glutamate subtype-2 and -3 (mGlu2/3) receptor positive allosteric modulators (PAMs): Pharmacological characterization and assessment in a rat model of cocaine dependence
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As part of our ongoing small-molecule metabotropic glutamate (mGlu) receptor positive allosteric modulator (PAM) research, we performed structure-activity relationship (SAR) studies around a series of group II mGlu PAMs. Initial analogues exhibited weak activity as mGlu2 receptor PAMs and no activity at mGlu3. Compound optimization led to the identification of potent mGlu2/3 selective PAMs with no in vitro activity at mGlu1,4-8 or 45 other CNS receptors. In vitro pharmacological characterization of representative compound 44 indicated agonist-PAM activity toward mGlu2 and PAM activity at mGlu 3. The most potent mGlu2/3 PAMs were characterized in assays predictive of ADME/T and pharmacokinetic (PK) properties, allowing the discovery of systemically active mGlu2/3 PAMs. On the basis of its overall profile, compound 74 was selected for behavioral studies and was shown to dose-dependently decrease cocaine self-administration in rats after intraperitoneal administration. These mGlu2/3 receptor PAMs have significant potential as small molecule tools for investigating group II mGlu pharmacology.
- Dhanya, Raveendra-Panickar,Sheffler, Douglas J.,Dahl, Russell,Davis, Melinda,Lee, Pooi San,Yang, Li,Nickols, Hilary Highfield,Cho, Hyekyung P.,Smith, Layton H.,D'Souza, Manoranjan S.,Conn, P. Jeffrey,Der-Avakian, Andre,Markou, Athina,Cosford, Nicholas D.P.
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p. 4154 - 4172
(2014/06/09)
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- Cobalt-bisoxazoline-catalyzed asymmetric kumada cross-coupling of racemic α-bromo esters with aryl grignard reagents
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The first cobalt-catalyzed asymmetric Kumada cross-coupling with high enantioselectivity has been developed. The reaction affords a unique strategy for the enantioselective arylation of α-bromo esters catalyzed by a cobalt-bisoxazoline complex. A variety of chiral α-arylalkanoic esters were prepared in excellent enantioselectivity and yield (up to 97% ee and 96% yield). The arylated products were transformed into α-arylcarboxylic acids and primary alcohols without erosion of ee. The new enantioenriched α-arylpropionic esters synthesized herein are potentially useful in the development of nonsteroidal anti-inflammatory drugs. This method was conducted on gram-scale and applied to the synthesis of highly enantioenriched (S)-fenoprofen and (S)-ar-turmerone.
- Mao, Jianyou,Liu, Feipeng,Wang, Min,Wu, Lin,Zheng, Bing,Liu, Shangzhong,Zhong, Jiangchun,Bian, Qinghua,Walsh, Patrick J.
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supporting information
p. 17662 - 17668
(2015/02/02)
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- Novel capsaicin analogues as potential anticancer agents: Synthesis, biological evaluation, and in silico approach
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A novel class of benzo[d][1,3]dioxol-5-ylmethyl alkyl/aryl amide and ester analogues of capsaicin were designed, synthesized, and evaluated for their cytotoxic activity against human and murine cancer cell lines (B16F10, SK-MEL-28, NCI-H1299, NCI-H460, SK-BR-3, and MDA-MB-231) and human lung fibroblasts (MRC-5). Three compounds (5f, 6c, and 6e ) selectively inhibited the growth of aggressive cancer cells in the micromolar (mM) range. Furthermore, an exploratory data analysis pointed at the topological and electronic molecular properties as responsible for the discrimination process regarding the set of investigated compounds. The findings suggest that the applied designing strategy, besides providing more potent analogues, indicates the aryl amides and esters as well as the alkyl esters as interesting scaffolds to design and develop novel anticancer agents. 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Damio, Mariana C. F. C. B.,Pasqualoto, Kerly F. M.,Ferreira, Adilson K.,Teixeira, Sarah F.,Azevedo, Ricardo A.,Barbuto, Jos A. M.,Palace-Berl, Fanny,Franchi-Junior, Gilberto C.,Nowill, Alexre E.,Tavares, Maurcio T.,Parise-Filho, Roberto
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p. 885 - 895
(2015/02/19)
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- Design, synthesis, and evaluation of novel VEGFR2 kinase inhibitors: Discovery of [1,2,4]triazolo[1,5-a]pyridine derivatives with slow dissociation kinetics
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For the purpose of discovering novel type-II inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2) kinase, we designed and synthesized 5,6-fused heterocyclic compounds bearing a anilide group. A co-crystal structure analysis of imidazo[1,2-b]pyridazine derivative 2 with VEGFR2 revealed that the N1-nitrogen of imidazo[1,2-b]pyridazine core interacts with the backbone NH group of Cys919. To retain this essential interaction, we designed a series of imidazo[1,2-a]pyridine, [1,2,4]triazolo[1,5-a]pyridine, thiazolo[5,4-b]pyridine, and 1,3-benzothiazole derivatives maintaining a ring nitrogen as hydrogen bond acceptor (HBA) at the corresponding position. All compounds thus designed displayed strong inhibitory activity against VEGFR2 kinase, and the [1,2,4]triazolo[1,5-a]pyridine 13d displayed favorable physicochemical properties. Furthermore, 13d inhibited VEGFR2 kinase with slow dissociation kinetics and also inhibited platelet-derived growth factor receptor (PDGFR) kinases. Oral administration of 13d showed potent anti-tumor efficacy in DU145 and A549 xenograft models in nude mice.
- Oguro, Yuya,Cary, Douglas R.,Miyamoto, Naoki,Tawada, Michiko,Iwata, Hidehisa,Miki, Hiroshi,Hori, Akira,Imamura, Shinichi
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p. 4714 - 4729
(2013/07/26)
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- Catalytic asymmetric reductive acyl cross-coupling: Synthesis of enantioenriched acyclic α,α-disubstituted ketones
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The first enantioselective Ni-catalyzed reductive acyl cross-coupling has been developed. Treatment of acid chlorides and racemic secondary benzyl chlorides with a NiII/bis(oxazoline) catalyst in the presence of Mn0 as a stoichiometric reductant generates acyclic α,α-disubstituted ketones in good yields and high enantioselectivity without requiring stoichiometric chiral auxiliaries or pregeneration of organometallic reagents. The mild, base-free reaction conditions are tolerant of a variety of functional groups on both coupling partners.
- Cherney, Alan H.,Kadunce, Nathaniel T.,Reisman, Sarah E.
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supporting information
p. 7442 - 7445
(2013/06/27)
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- Bromination of enamines from tertiary amides using the petasis reagent: A convenient one-pot regioselective route to bromomethyl ketones
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An original one-pot synthesis of bromomethyl ketones is achived using the Petasis reagent (dimethyltitanocene) as a key for enamine generation. Several amides were used to test the limits of the procedure by changing either the alkyl chain R or the amino portion of the starting materials. The enamines generated in situ were allowed to react with bromine at low temperature followed by hydrolysis to yield bromomethyl ketones in excellent yields (85 to 95%). Mechanistic details and optimum conditions for the reaction are briefly discussed. The present approach offers several advantages such as regioselectivity in enamine formation, good yields, mild reaction conditions, and ease of experimentation.
- Kobeissi, Marwan,Cherry, Khalil,Jomaa, Wissam
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supporting information
p. 2955 - 2965
(2013/09/02)
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- Anti-HIV and NO production inhibition activities of epi-aleuritolic acid derivatives
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Fifteen epi-aleuritolic acid derivatives were synthesized and evaluated for anti-HIV activity in 293 T cells and NO production inhibition activity. Of the derivatives, 1, 2, 3, 4, 11, and 13 showed relatively potent anti-HIV activity with EC50 values ranging from 5.80 to 13.30 μM. The most potent compound, 3α-2′,2′-dimethylsuccinic acyl epialeuritolic acid (11), displayed significant anti-HIV activity with an EC50 value of 5.80 μM. Compounds 1, 3, 4, and 11 showed NO inhibition activity, with IC50 values ranging from 3.40 to 7.10 μM and compound 1 inhibited NO production with an IC50 value of 3.40 μM.
- Liu, Jia-Bao,Zhang, Ying,Cui, Bao-Song,Cao, Ying-Li,Yuan, Shao-Peng,Guo, Ying,Hou, Qi,Li, Shuai
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p. 515 - 524
(2013/09/02)
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- POSITIVE ALLOSTERIC MODULATORS OF MGLUR2
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The disclosure generally relates to compounds of formula I, including their salts, as well as compositions and methods of using the compounds. The compounds modulate the mGluR2 receptor and may be useful for the treatment of various disorders of the central nervous system. Formula (I):
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Page/Page column 96
(2014/01/09)
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- A simple method for asymmetric trifluoromethylation of N-acyl oxazolidinones via Ru-catalyzed radical addition to zirconium enolates
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A Ru-catalyzed direct thermal trifluoromethylation and perfluoroalkylation of N-acyloxazolidinones has been developed. The reaction is experimentally simple and requires inexpensive reagents while providing good yields of products with good levels of stereocontrol. Preliminary studies have shown notable compatibility with functional groups, aromatics, and certain heteroaromatic substituents. The described method provides a useful alternative for the synthesis of fluorinated materials in an experimentally convenient manner.
- Herrmann, Aaron T.,Smith, Lindsay L.,Zakarian, Armen
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supporting information; experimental part
p. 6976 - 6979
(2012/06/15)
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- Identification and synthesis of three cyclodidepsipeptides as potential precursors of enniatin B in Fusarium sporotrichioides
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A pathogenic fungus, Fusarium sporotrichioides Sherb., was isolated from Hypericum barbatum Jacq. The volatile compounds of broth and mycelium were analyzed using GC-MS and three cyclodidepsipeptides (dioxomorpholines), 3,6-di(propan-2-yl)-4-methyl-morpholine-2,5-dione, 3-(2-methylpropyl)-6-(propan- 2-yl)-4-methyl-morpholine-2,5-dione and 3-(butan-2-yl)-6-(propan-2-yl)-4-methyl- morpholine-2,5-dione, were found for the first time in the natural products. The structures of the compounds were confirmed by comparison of the analytical data for the natural products with samples obtained via synthetic methods. The conformational features and vibrational spectra of the three cyclodidepsipeptides were characterized by density functional theory (DFT) calculations and IR spectroscopy. The cyclic hexadepsipeptide enniatin B was identified by a LC-MS/MS analysis of the non-volatile products of broth and mycelium. The above-mentioned three cyclodidepsipeptides are probably synthesized using similar biosynthetic ways to enniatin B involving a nonribosomal mechanism.
- Smelcerovic, Andrija,Yancheva, Denitsa,Cherneva, Emiliya,Petronijevic, Zivomir,Lamshoeft, Marc,Herebian, Diran
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experimental part
p. 397 - 402
(2011/04/14)
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- Copper-catalyzed aerobic oxidative cyclization of hydrazones to pyrazolidinones
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N-Aryl hydrazones participate, under copper catalysis, in a [3+2] cycloaddition/aerobic oxidation cascade reaction to form pyrazolidinones. The starting hydrazones were prepared by three-component coupling of allylic amines, acyl chlorides, and aryl diazonium salts. Copyright
- Dos Santos, Aurelie,El Kaim, Laurent,Grimaud, Laurence,Ronsseray, Caroline
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supporting information; experimental part
p. 3117 - 3121
(2011/07/29)
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- Synthesis of 4-quinolones via cyclocondensation of substituted ortho-amidoacetophenones: A refit to the camps cyclization by applying trimethylsilyl trifluoromethanesulfonate/triethylamine
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A modification of the classical Camps cyclization is described. A series of substituted 4-quinolone derivatives is prepared via trimethylsilyl trifluoromethanesulfonate/triethylamine induced cyclocondensation of substituted ortho-amidoacetophenones. The process shows a broad substrate scope and allows selective preparation of 2-aryl- and 2-alkyl-substituted 4-quino-lones. Enantiopure starting materials react without loss of optical purity using the modified conditions. Subsequent transformations of the products involving preparation of a 4-quinolyl nonaflate and O-selective methylation are also described. Georg Thieme Verlag Stuttgart · New York.
- Eidamshaus, Christian,Triemer, Therese,Reissig, Hans-Ulrich
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supporting information; experimental part
p. 3261 - 3266
(2011/11/30)
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- MODIFIED POLYOLEFIN WAXES
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Described is a method for modifying the thermal softening behaviour of a polyolefin wax, which comprises the incorporation into the wax of at least one compound of the formula (I) wherein Q is a C3-C12alkyltriyl, a tris(C1-C8alkylene)amine, a C3-C12cycloalkyltriyl or is of the formula (II), or X1, X2 and X3 are independently from each other -NH-CO-NH-, -NH-CO-O-, -O-CO-NH-, - NH-CO-, -CO-NH, -COO- or -0-; R1, R2 and R3 are various unsubstituted or substituted aliphatic or aromatic radicals.
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Page/Page column 37
(2010/08/05)
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- Antinociceptive effect of extracts and compounds from Hofmeisteria schaffneri
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Ethnopharmacological relevance: Hofmeisteria schaffneri (Asteraceae) is a medicinal plant widely commercialized in the most important Markets of Mexico City for the treatment of gastro-intestinal complaints and skin afflictions. Aim of the study: The main goals of this study were to establish the potential acute toxicity and the antinociceptive activity in animal models of several preparations and compounds from Hofmeisteria schaffneri. Materials and methods: The aqueous and organic extracts as well as the essential oil of Hofmeisteria schaffneri were prepared by infusion, maceration and hydrodistillation, respectively. Investigation of the acute toxicity was accomplished by the Lorke method. The antinociceptive effect was assessed using the writhing and the hot plate tests. Natural compounds were isolated by standard phytochemical procedures. In addition, a few thymol esters were prepared by chemical synthesis. The stability of natural and synthetic esters was qualitatively analyzed by measuring their susceptibility to hydrolysis by pig liver estearase and mouse plasma at 37°C. Results: The LD50 for each preparation tested was higher than 5000mg/kg revealing that they were not toxic to mice after exposure for short space of time. On the other hand, the extracts showed significant antinociceptive effect when tested in the hot plate model. The most active natural product as antinociceptive agent was hofmeisterin III (1) which also was the most stable in the stability study. Its pharmacological effect seems to be partially mediated by an opioid mechanism since naloxone inhibits its action. Using compound 1 as a lead molecule, several synthetic thymol esters were prepared and only compounds 13, 15 and 17 were antinoceptive at the dose of 1mg/kg. Conclusions: The present investigation provided evidence of the efficacy of several preparations of Hofmeisteria schaffneri as antinociceptive agents. The most active preparation was the essential oil which contained large amount of hofmeisterin III (1) and other thymol derivatives. Some novel synthetic analogs of hofmeisterin III with antinociceptive properties were discovered. The nature of the ester chain of these analogs did not have a clear impact on the antinociceptive activity. The phyto-preparations analyzed in this study were not toxic to mice according to the Lorke's test; therefore considering their long term use of the plant they might be secure for human consumption.
- Angeles-Lopez, Guadalupe,Perez-Vasquez, Araceli,Hernandez-Luis, Francisco,Deciga-Campos, Myrna,Bye, Robert,Linares, Edelmira,Mata, Rachel
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experimental part
p. 425 - 432
(2011/11/14)
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- Chemical composition of Inula cuspidata C.B. Clarke
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Thymyl isobutyrate, thymol, thymyl isovalerate, 8α-hydroxy presilphiperfolene and intermedeol have been isolated from steam volatile extract of Inula cuspidata and identified from their spectral data, synthesis and chemical modification of major constituents. Sharp qualitative and quantitative variations among the constituents of leaf, flower and roots of Inula cuspidata are noticed.
- Mathela,Tiwari,Padalia,Chanotiya
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p. 1249 - 1253
(2008/12/23)
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- Synthesis of carnitine benzyl esters as prodrugs
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The introduction of C-2 acyl groups and a benzyl ester onto L-carnitine generated a series of carnitine benzyl esters as prodrug with improved liposolubility, stability and bioavailability.
- Gong, Xiao-Wei,Li, Jin-Pei,Wu, Ji-Feng,Li, Xun,Zhai, Hai-Min,Feng, Bo,Xu, Wen-Fang,Tang, Wei
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experimental part
p. 327 - 330
(2009/05/30)
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- Structure activity studies with xenobiotic substrates using carboxylesterases isolated from Arabidopsis thaliana
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Carboxylesterases (CXEs) catalyse the hydrolysis of xenobiotics and natural products radically altering their biological activities. Whereas the substrate selectivity of animal CXEs, such as porcine liver esterase (PLE) have been well studied, the respective enzymes in plants have yet to be defined and their activities determined. Using Arabidopsis thaliana (At) as a source, five representative members of the α/β hydrolase AtCXE family of proteins have been cloned, expressed and the purified recombinant proteins assayed for esterase activity with xenobiotic substrates. Two members, AtCXE5 and AtCXE18 were found to be active carboxylesterases, though AtCXE5 proved to be highly unstable as a soluble protein. AtCXE18 and the previously characterised S-formylglutathione hydrolase from Arabidopsis (AtSFGH) were assayed against a series of esters based on methylumbelliferone in which the acyl moiety was varied with respect to size and conformation. The same series was used to assay crude esterase preparation from Arabidopsis plants and the results compared with those obtained with the commonly used PLE. With straight chain esters, AtCXE18 behaved like PLE, but the Arabidopsis hydrolases proved less tolerant of branched chain acyl components than the mammalian enzyme. While none of the enzyme preparations accurately reflected all the activities determined with crude Arabidopsis protein extracts, the plant enzymes proved more useful than PLE in predicting the hydrolysis of the more sterically constrained esters.
- Cummins, Ian,Landrum, Marie,Steel, Patrick G.,Edwards, Robert
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p. 811 - 818
(2008/03/13)
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- Synthesis of esters of D, L-, D(+)-, and L(-)-camphor oximes: Structure-odor correlation
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Esters of D,L-, D(+)-, and L(-)-camphor oximes were synthesized, and the correlation between their structure and odor was examined.
- Dikusar,Zhukovskaya,Vyglazov
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p. 1982 - 1985
(2008/02/08)
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- A practical access to α-phosphonoenamides
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Reaction of α-oximinophosphonates first with acetic anhydride then with iron powder and acetic acid at 50-60 °C results in the clean formation of an E-Z mixture of α-phosphonoenacetamides, which are immediate precursors to α-aminophosphonic acids.
- Quiclet-Sire, Béatrice,Zard, Samir Z.,Zhang, Haiwen
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p. 404 - 408
(2007/10/03)
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- Chlorination of Carboxylic Acid Derivatives. VIII. Liquid Phase Chlorination of the Aliphatic C5-Carboxylic Acids and Their Chlorides, Methyl Esters and Chloromethyl Esters with Chlorine
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The chlorination of pentanoic, 3-methylbutanoic, 2-methylbutanoic and 2,2-dimethylpropanoic acids and their derivatives with chlorine in the liquid phase have been investigated.The monochloro products formed were determined by gas-liquid chromatography (GLC) and gas-liquid chromatography-mass spectrometry (GLC-MS) as their esters through the comparison with authentic samples.The deactivation of position 2 decreases in the order COCl > CO2H > CO2CH2Cl > CO2CH3, the effect of the COCl-group in pentanoic acid derivatives being 4.3 times stronger than that of the CO2CH3-group.The deactivation is smallest in 2-methylbutanoic acid derivatives owing to the electron-donating methyl group.The EI mass spectra of the methyl and chloromethyl esters have been studied in detail.
- Kornonen, Ilpo O. O.
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p. 467 - 474
(2007/10/02)
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- 2-Acyl-3-substituted cyclopentan-1-ones and process for their preparation
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1,3-Dicarbonyl compounds useful as medicines, agricultural chemicals, perfumes, and their intermediates are prepared by reacting a specific α,β-unsaturated carbonyl compound with a specific organic copper lithium compound in the presence of an aprotic inert organic solvent, and then reacting the reaction product with an organic carboxylic acid halide or anhydride. In particular, novel 2-acyl-3-substituted cyclopentan-1-ones and 2-acyl-3-substituted cyclohexan-1-ones having important physiological activities are provided.
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- SYNTHESIS OF SOME NEW CHOLESTERYL ESTERS OF CHIRAL ALKANOIC ACIDS.
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Six new cholesteryl esters have been prepared from chiral alkanoic acids. Oxidation of 2(S)-methylbutanol and 2(S)-ethyl-3-methybutyraldehyde gave the corresponding butyric acids, while condensation of the tosylates of the corresponding alcohols with diethyl malonate led ultimately to the substituted hexanoic acids. 2(R)-Methylpentanoic and ( minus )-2-ethylhexanoic acids were commercially available.
- Gibson
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